The invention pertains to methods of forming insulating material, such as for example, methods of forming insulating material between components of integrated circuits.
In methods of forming integrated circuits, it is frequently desired to isolate components of the integrated circuits from one another with insulative material. Such insulative material may comprise a number of materials, including, for example, silicon dioxide, silicon nitride, and undoped semiconductive material, such as silicon. Although such materials have acceptable insulative properties in many applications, the materials disadvantageously have high dielectric constants which can lead to capacitive coupling between proximate conductive elements. For instance, silicon dioxide has a dielectric constant of about 4, silicon nitride has a dielectric constant of about 8, and undoped silicon has a dielectric constant of about 12.
It would be desirable to develop alternative methods for insulating conductive elements from one another with low-dielectric-constant materials.
The invention encompasses methods of forming insulating materials proximate conductive elements.
In one aspect, the invention encompasses a method of forming an insulating material proximate a substrate in which a first material is chemical vapor deposited proximate the substrate. Cavities are formed within the first material, and, after forming the cavities, at least some of the first material is transformed into an insulative second material.
In another aspect, the invention encompasses a method of forming an insulating material proximate a substrate in which porous polysilicon is formed proximate the substrate and at least some of the porous polysilicon is transformed into porous silicon dioxide.
In yet another aspect, the invention encompasses a method of forming an insulating material between components of an integrated circuit. Polysilicon is chemical vapor deposited between two components and electrochemically anodized to convert the polysilicon into a porous mass having a first volume. The first volume comprises a polysilicon volume and a cavity volume, with the cavity volume comprising greater than or equal to about 75% of the first volume. The porous polysilicon mass is oxidized to transform the polysilicon into porous silicon dioxide having a second volume. The second volume comprises a silicon dioxide volume and a cavity volume, with the cavity volume comprising less than or equal to about 50% of said second volume.